Europium-doped Yttrium Oxide Research Articles

Eu-doped Y2O3 phosphor films produced by electrostatic-assisted chemical vapor deposition

Europium-doped yttrium oxide (Y2O3:Eu) thermographic phosphor films were deposited on Ni-alloy substrates using a novel and cost-effective electrostatic-assisted chemical vapor deposition (EACVD) technique. The thermoluminescence properties were studied under irradiation by an ultraviolet laser. It was found that crystallized Y2O3: Eu films could be deposited at a temperature as low as 550 °C. Annealing of the as-deposited films at higher temperatures (>1000 °C) improved the luminescence properties due to further crystallization processes. The correlation of the lifetime decay and temperature change of the films showed that the EACVD-deposited films are suitable for use in phosphor thermometry for high-temperature applications.

Luminescence behavior of pulsed laser deposited Eu:Y2O3 thin film phosphors on sapphire substrates

Europium-doped yttrium oxide (Eu:Y2O3) luminescent thin films have been grown in situ on single crystal (0001) sapphire substrates using a pulsed laser deposition technique. The films grown under different deposition conditions have been characterized using microstructural and luminescent measurements. The photoluminescence (PL) and cathodoluminescence (CL) brightness data obtained from the Eu:Y2O3 films grown under optimized conditions have indicated that sapphire is a promising substrate for the growth of high quality Eu:Y2O3 thin film red phosphor. The success in the fabrication of Eu:Y2O3 films with high PL and CL brightness is attributed to favorable optical properties (low absorption of and low refractive index for red light) of the substrate material and improved growth of grains with unidirectional orientation on (0001) sapphire substrates.

Luminescence of pulsed laser deposited Eu doped yttrium oxide films

Europium doped yttrium oxide (Eu:Y2O3) phosphor thin films were grown using a pulsed laser deposition (PLD) technique at varying growth conditions. The structural characterization carried out on a series of Eu:Y2O3 films grown on (100) silicon at substrate temperatures in the range of 250–600 °C and oxygen pressure in the range of 10−5 Torr to 200 mTorr indicated that films were preferentially (111) oriented. Measurements of photoluminescence and cathodoluminescence properties of laser deposited Eu:Y2O3 thin films and powder used for laser target showed that the best in situ grown films were ∼10%–22% as bright as Eu:Y2O3 powder. A postdeposition annealing treatment of Eu:Y2O3 films led to further improvements in their brightness (up to ∼70% with respect to Eu:Y2O3 powder), with cluster sizes of <400 nm.

Microstructural and Photoluminescence Studies on Europium Doped Yttrium Oxide Films Synthesized by Metallorganic Vapor Deposition

ABSTRACTThe microstructural and luminescence properties of europium doped yttrium oxide (Y2O3:Eu) thin films deposited by metallorganic chemical vapor deposition are presented in this work. It was found that surface morphology, crystallinity and photoluminescent emission properties are strongly dependent on substrate temperature during deposition. The depositions were carried out in a stainless steel chamber using yttrium and europium 2,2,6,6,-tetramethyl–3,5-heptanedionates as volatile precursors and O2 as the reactant gas. Post-annealing increased the crystallite size and decreased the lattice parameter, resulting in an increased photoluminescent emission intensity.

Spectra of europium-doped yttrium oxide and yttrium vanadate phosphors

The spectral distributions of the visible absorption and fluorescence emission under electron beam excitation of Eu3+-doped (Y2O3) and (YVO4) powders have been detected and analyzed. (Y2O3: Eu3+) has a cubicC crystal structure with a unit cell dimension a=10·61 A. Its observed transitions from7 F 0 to many upper states have been recognized; the observed number of Stark components is in agreement with that based on theC 2 site symmetry of the Eu3+ ion in Y2O3. Eu3+-doped yttrium vanadate has a typical zircon tetragonal crystal structure with unit cell dimensions ofc=6·29 A anda=7·11 A. The observed transitions in (Eu3+: YVO4) have been identified and assigned in accordance with theD 2d site symmetry of the Eu3+ ion in this lattice.

Precise determination of nanogram quantities of europium by the combination of gravimetric sample preparation and neutron activation γ-ray spectrometry

The precision of the determination of nanogram quantities of europium was increased greatly through the gravimetric sampling of standard and sample solutions. About 3 mg(≈0.003 ml) of europium solutions (1100 μg-Eu/ml) was weighed out by means of a polyethylene pycnometer (Fig. 1) and spottes on a piese of filter paper (0.5 cm in diameter). The filter paper was dried at room temperature and sealed in a polyethylene pouch.The sample was irradiated, together with a standard in a pneumatic tube of JRR-2 at a neutron flux of 7.0×1013 neutron·cm-2·sec-1 for 1 minute. 151Eu (natural abundance 47.77%) is nuclearly trasformed through 151Eu(n, γ) 152mEu to 152Eu, which decays as152mEu β-, γ(0.842 MeV, 0.961 MeV)→T1/2:9.2h152Eu β-, γ→T1/2:12.7 years 152GdThe radioactivity of 152mEu was measured by a high resolution Ge(Li)-detector and 1024 channel pulse height analyzer.The repeatability precision of the method was 0.418% in terms of coefficient of variation for 4ng of europium, this value being higher than theoretical precision calculated from statistical fluctuation. The corresponding values were 2.3% and 5.20%, when a 1-ml pipette and a 10-μl microsyringe were used, respectively, for the sampling. The adoption of the gravimetric sampling and activation γ-ray spectrometry allowed the determination of nanogram quantities of europium with an error of 0.5% or less.The procedure was applied to the test of local distribution of europium in red phosphors (europiumdoped yttrium oxide).About 0.5 mg of the sample powder was weighed by a semi-micro balance, transfered to the weighed weighing vial, then dissolved in 5 ml of 2 M HNO3, and the weight of the solution was determined.About 1 ml of the solution was introduced into a pycnometer, and europium was determined according to the above-described procedure. This experiment revealed that the doped europium was not uniformly distributed in commercial red phosphors from a microscopic point of view.